Cognitive Function Post-Transplantation

Kidney disease is known to negatively affect cognition. Aditi Gupta, MD, MS, and other researchers questioned the effect of kidney transplantation (KT) on cognitive abilities. They examined the effect of KT on different areas of cognition in a prospective cohort study of patients waitlisted for KT at an academic center. 

The team measured cognitive function before KT (n=101), 3 months after KT (n=78), and 1 year after KT (n=83). The primary outcome was the change in cognitive function before versus after KT. They used tests for global cognition (Mini-Mental State Exam [MMSE]), episodic/declarative memory (Logical Memory), psychomotor speed/visuospatial function (Digit Symbol Substitution Test [DSST], Trail Making Test [TMT] A), working memory/attention (Digit Span), executive function (TMT B), and semantic memory/verbal fluency/language (Category Fluency). Using linear mixed model analysis, the researchers evaluated the changes in neuropsychological test scores adjusted for age, sex, race, education, and number of assessments. 

Episodic and verbal declarative memory were found to normalize after KT, while semantic memory, verbal fluency, language, psychomotor speed, and visuospatial function showed partial improvement. 

Prior to KT, Logical Memory I and II, DSST, MMSE, Category Fluency (animal naming), and Digit Span backward scores were low compared to normative values from the National Alzheimer’s Coordinating Center data. Logical Memory I and II scores improved after KT (pre- vs post-KT: estimated group difference [d], 3.3; P<.001 for Logical Memory I; d, 4.27; P<.001 for Logical Memory II); post-KT scores were comparable with normative values (post-KT vs normative values: d, −0.37; P=.06 for Logical Memory I; d, −0.89; P=.08 for Logical Memory II). Category Fluency (d, 2.40; P<.001) and DSST (d, 3.12; P=.01) scores improved with KT, although post-KT DSST scores remained lower than normative values (post-KT vs normative values: d, −5.17; P<.001). MMSE, Digit Span, and TMT A and B scores did not change post-KT. 

In sum, cognitive impairment in kidney disease is at least partially reversible with KT. 

Source: American Journal of Kidney Diseases